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Fix bug for cumulative compaction on singleton rowset with multiple segments (#2719)

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Row will be scanned mistakenly after cumulative compaction on singleton rowset.
If I have (1, 1), (2, 2), (3, 3) three records.
Now I have read (1, 1), this bug will make return row is (2, 2)
instead of (1, 1).
This commit is contained in:
lichaoyong
2020-01-09 21:08:21 +08:00
committed by Mingyu Chen
parent e7b763309d
commit fa4407cf4f
1 changed files with 15 additions and 3 deletions
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18
be/src/olap/rowset/alpha_rowset_reader.cpp
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@ -156,6 +156,18 @@ OLAPStatus AlphaRowsetReader::_merge_block(RowBlock** block) {
copy_row(_dst_cursor, *row_cursor, _read_block->mem_pool());
_read_block->pos_inc();
num_rows_in_block++;
// MergeHeap should advance one step after row been read.
// This function must be called after copy_row
// Otherwise, the row has read will be modified instantly before handled.
// For example:
// If I have (1, 1), (2, 2), (3, 3) three records.
// Now I have read (1, 1).
// Before copy_row, I rebuild the heap
// The returned row will be (2, 2) instead of (1, 1)
AlphaMergeContext* merge_ctx = _merge_heap.top();
_merge_heap.pop();
RETURN_NOT_OK(_update_merge_ctx_and_build_merge_heap(merge_ctx));
}
_read_block->set_pos(0);
_read_block->set_limit(num_rows_in_block);
@ -205,9 +217,9 @@ OLAPStatus AlphaRowsetReader::_pull_next_row_for_merge_rowset_v2(RowCursor** row
if (!_merge_heap.empty()) {
AlphaMergeContext* merge_ctx = _merge_heap.top();
*row = merge_ctx->row_cursor.get();
_merge_heap.pop();
RETURN_NOT_OK(_update_merge_ctx_and_build_merge_heap(merge_ctx));
// Must not rebuild merge_heap in this place.
// Because row have not been copied and is a pointer.
// If rebuild merge_heap, content in row will be modified.
return OLAP_SUCCESS;
} else {
// all rows are read